Cooling apparatus

ABSTRACT

Fins are each formed with a flat shape in a height direction, which is orthogonal to a flow direction of coolant in a coolant passage, and a plurality of the fins are provided intermittently along virtual waveforms extending in the flow direction and making a plurality of rows in a width direction that is orthogonal to the height direction and to the flow direction. An upstream portion of a first fin provided in a first row overlaps with the position in the flow direction f of a downstream portion of a second fin provided in a second row adjacent to the first row. Furthermore, the downstream portion of the first fin overlaps with a position in the flow direction of an upstream portion of a third fin provided in the second row.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-228527 filed on Nov. 29, 2017, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a cooling apparatus including a plurality of fins within a coolant passage that is near a heat source body.

Description of the Related Art

An electric automobile or hybrid automobile using an electric motor as a drive source includes a drive circuit that converts the power supplied from a high voltage power source into power for driving the motor, and supplies this power to the motor. Since the drive circuit generates heat along with the driving, a cooling apparatus is provided near the drive circuit. For example, a coolant passage including a heat sink therein is used as the cooling apparatus.

Japanese Laid-Open Patent Publication No. 2016-205802 shows a cooling apparatus that includes wave-shaped fins extending in the direction of the flow of coolant within the coolant passage. By bending the top end portion of each fin in the width direction of the coolant passage, an opening portion is formed between the downstream side end portions of the upstream side fins and the upstream side end portions of the downstream fins.

SUMMARY OF THE INVENTION

There is a cooling apparatus in which a series of fins are provided from an upstream side to a downstream side. In this cooling apparatus, since the coolant flows while contacting the fins, it is easy for the coolant that continues flowing near the fins to accumulate heat. Therefore, a temperature boundary layer is prone to occurring near the fins on the downstream side. On the other hand, in the cooling apparatus shown in Japanese Laid-Open Patent Publication No. 2016-205802, the coolant flows while contacting the fins and becomes distanced from the fins at the opening portion. Because of this, the temperature accumulated in the coolant is cancelled for the moment. Therefore, it is difficult for the temperature boundary layer to form near the fins on the downstream side.

However, in the cooling apparatus shown in Japanese Laid-Open Patent Publication No. 2016-205802, the flow rate of the coolant in a part of the location where the fins and coolant are in contact becomes low, and in a worst case scenario, retention of the coolant occurs. In this way, although the flow of the coolant at locations distanced from the fins is maintained, the flow of the coolant near the fins becoming extremely slow, and this is referred to as separation. The heat releasing efficiency at the separation location of the flow of the coolant is reduced.

The present invention takes into consideration such a problem, and it is an object of the present invention to provide a cooling apparatus that can realize favorable heat transfer between fins and a coolant.

The present invention is a cooling apparatus comprising a plurality of fins within a coolant passage near a heat source body, wherein the plurality of fins each have a flat shape in a height direction orthogonal to a flow direction of coolant in the coolant passage, and are provided intermittently along virtual waveforms that extend in the flow direction and that make a plurality of rows in a width direction orthogonal to the flow direction and to the height direction, and with a fin provided in a first row being a first fin and two fins lined up in the flow direction and provided in a second row adjacent to the first row being a second fin and a third fin, an upstream portion including an upstream end of the first fin overlaps with a position in the flow direction of a downstream portion including a downstream end of the second fin, and a downstream portion including a downstream end of the first fin overlaps with a position in the flow direction of an upstream portion including an upstream end of the third fin.

With the above configuration, it is possible to restrict the development of the temperature boundary layer by providing the fins intermittently in the flow direction of the coolant. Furthermore, by causing the positions of the upstream portion of the first fin provided in the first row and the downstream portion of the second fin provided in the second row adjacent thereto to overlap in the flow direction and also causing the positions of the downstream portion of the first fin provided in the first row and the upstream portion of the third fin provided in the second row to overlap in the flow direction, it is possible to restrict the flow of the coolant from separating from the fins. With the structure described above, favorable heat transfer can be realized between the fins and the coolant.

In the present invention, the fins may be provided along portions of the waveforms including two peaks.

With the above configuration, development of the temperature boundary layer and separation of the flow of coolant are further restricted, and favorable heat transfer can be realized between the fins and the coolant.

In the present invention, the waveforms may have shapes symmetrical on an axis that is a virtual line that passes through the peaks, is orthogonal to the flow direction, and is parallel to the width direction.

With the above configuration, separation of the flow of coolant is further restricted, and favorable heat transfer can be realized between the fins and the coolant.

In the present invention, the fins may each have the same shape in cross-sectional planes parallel to the flow direction and to the width direction.

With the above configuration, favorable heat transfer can be realized over a wide range, with coolant flow that is substantially uniform in the height direction.

In the present invention, favorable heat transfer can be realized between the fins and the coolant.

In the present embodiment, in a case where a length of a half wavelength of the waveform in the flow direction is λ/2 and a length of the fin in the flow direction is L, [{L−(λ/2)}/λ/2]×100 may be greater than or equal to 30% and less than 50%.

With the configuration described above, the effect of preventing the occurrence of the separation is realized.

The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the cooling apparatus according to the present embodiment.

FIG. 2 is an exploded perspective view of the cooling apparatus according to the present embodiment.

FIG. 3 is a partial plan view of an inner fin.

FIG. 4 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row relative to the first row is 0%.

FIG. 5 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row relative to the first row is 15%.

FIG. 6 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row relative to the first row is 25%.

FIG. 7 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row relative to the first row is 50%.

FIG. 8 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 0%.

FIG. 9 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 5%.

FIG. 10 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 10%.

FIG. 11 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 30%.

FIG. 12 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 40%.

FIG. 13 is a table showing results obtained by examining the velocity vectors and temperature contours while changing the offset amounts and the extension amounts, while using fins with amplitudes of 1 [mm].

FIG. 14 is a table showing results obtained by examining the velocity vectors and temperature contours while changing the offset amounts and the extension amounts, while using fins with amplitudes of 3 [mm].

FIG. 15 is a table showing results obtained by examining the velocity vectors and temperature contours while changing the offset amounts and the extension amounts, while using fins with amplitudes of 5 [mm].

FIG. 16 is a partial plan view of an inner fin according to another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following describes the present invention while providing examples of preferred embodiments and referencing the accompanying drawings.

1. Cooling Apparatus 10

The cooling apparatus 10 shown in FIG. 1 has a flat shape, and is provided near a bottom surface of a PCU (power control unit) of an electric vehicle such as an electric automobile of hybrid automobile. The PCU is a heat source body that generates heat when supplying power from a high voltage battery to an electric motor or when supplying power from a generator to a high voltage battery.

As shown in FIG. 2, the cooling apparatus 10 includes a top cover 20, a bottom cover 30, and an inner fin 40. The top cover 20, bottom cover 30, and inner fin 40 are formed of metal with high thermal conductivity, such as aluminum or copper that has undergone nickel plating. The top surface of the top cover 20 is used as a heat absorbing surface. A side wall 32 protruding upward is formed on the circumferential edge of the bottom cover 30, and two holes penetrating from the bottom surface to the top surface are formed at respective ends of the bottom cover 30 in the longitudinal direction. One of these holes is used as a flow inlet 34 for the coolant, and the other hole is used as a flow outlet 36 for the coolant.

The inner fin 40 includes a board portion 42 brazed to the bottom cover 30 and a plurality of fins 44 that protrude upward from the board portion 42. The bottom surface of the board portion 42 is brazed to the top surface of the bottom cover 30. The bottom surface of the top cover 20 is brazed to the top end of the side wall 32 of the bottom cover 30, or contacts the top end of each fin 44. In this way, a coolant passage 12 through which coolant flows is formed by the bottom cover 30 and the top cover 20, and a plurality of fins 44 are provided within the coolant passage 12. The flow direction f of the coolant in the coolant passage 12 is substantially parallel to the longitudinal direction.

2. Fins 44

In the present embodiment, the shape and arrangement of the fins 44 are one characteristic. The shape and arrangement of the fins 44 are described using FIG. 3. In FIG. 3, the left-right direction in the plane of the drawing matches the longitudinal direction of the cooling apparatus 10, and the up-down direction in the plane of the drawing matches the width direction. Furthermore, although not shown in the drawing, a direction perpendicular to the plane of the drawing matches the height direction.

As shown in FIG. 3, in the plan view of the inner fin 40, a plurality of waveforms 60 extending in the flow direction f are assumed. In FIG. 3, sinusoidal curves are shown as an example of the waveforms 60. The amplitudes and periods of the waveforms 60 are substantially constant from the upstream side to the downstream side in the flow direction f. Furthermore, the phases of the plurality of waveforms 60 are the same as each other at each position in the flow direction f. Each waveform 60 forms a shape that has linear symmetry, with a virtual line 70. The virtual line 70 passes through a peak 62, is orthogonal to the flow direction f, and is parallel to the width direction serving as an axis.

Each fin 44 is provided intermittently along the waveform 60. In other words, in a single waveform 60, a gap 46 is provided between the two fins 44 in front and behind along the flow direction f, and the fins 44 and gaps 46 are arranged in a row in an alternating manner. One wavelength of the waveform 60 is formed by combining one fin 44 and one gap 46 that are adjacent to each other.

The fin 44 is formed along a portion of the waveform 60 including two peaks 62. The portion of the fin 44 arranged on the peak 62 on the upstream side is referred to as an upstream side peak portion 48, and the portion of the fin 44 formed on the peak 62 on the downstream side is referred to as a downstream side peak portion 50. The portion of the fin 44 arranged farthest on the upstream side in the flow direction f is referred to as the upstream end 52, and the portion of the fin 44 arranged farthest on the downstream side is referred to as the downstream end 54. The upstream end 52 is at a position resulting from the fin 44 being extended to the upstream side from the upstream side peak portion 48 along the waveform 60, and the downstream end 54 is at a position resulting from the fin 44 being extended to the downstream side from the downstream side peak portion 50 along the waveform 60. Therefore, the length L of the fin 44 in the flow direction f is greater than the length λ/2 of the half wavelength of the waveform 60. Details of the extension amount by which the fin 44 extends from the upstream side peak portion 48 to the upstream end 52 and the extension amount by which the fin 44 extends from the downstream side peak portion 50 to the downstream end 54 are provided in section [4] below.

There are two arrangement patterns for the fins 44 and the gaps 46. One of these arrangement patterns is a first pattern in which the position of the fin 44 in the width direction is displaced in one direction (e.g., to an upward direction in the plane of the drawing of FIG. 3) as progression occurs along the fin 44 from the upstream side peak portion 48 to the downstream side peak portion 50. The other arrangement pattern is a second pattern in which the position of the fin 44 in the width direction is displaced in the other direction (e.g., a downward direction in the plane of the drawing of FIG. 3) as progression occurs along the fin 44 from the upstream side peak portion 48 to the downstream side peak portion 50. First rows 72 of the first pattern and second rows 74 of the second pattern are lined up in an alternating manner from one side to another side in the width direction. The intervals P between adjacent first rows 72 are constant, and the intervals P between adjacent second rows 74 are also constant. Details about the intervals Po (Po1 and Po2) between the first rows 72 and the second rows 74 are provided in section [3] below. In FIG. 3, an implementation state is shown in which the first rows 72 and second rows 74 are lined up from one side to the other in the width direction at uniform intervals P/2 (=0.50 P).

In a fin 44, the portion from the upstream side peak portion 48 to the upstream end 52 and the portion having line symmetry with respect to this portion using the virtual line 70 as an axis are referred to collectively as the upstream portion 56. Furthermore, in a fin 44, the portion from the downstream side peak portion 50 to the downstream end 54 and the portion having line symmetry with respect to this portion using the virtual line 70 as an axis are referred to collectively as a downstream portion 58. The upstream portion 56 of the fin 44 arranged in the first row 72 overlaps with the position of the downstream portion 58 of a fin 44 arranged in the second row 74 in the flow direction f. The downstream portion 58 of a fin 44 arranged in the first row 72 overlaps with the position of the upstream portion 56 of a fin 44 arranged in the second row 74 in the flow direction f.

Each fin 44 has a constant height from the upstream end 52 to the downstream end 54, and has a flat shape in the height direction in accordance with the cooling apparatus 10. Furthermore, the fins 44 have the same shape in each of cross-sectional planes parallel to both the flow direction f and the width direction. In other words, the fins 44 have the same shapes as seen in the plan view of FIG. 3. The fins 44 have the same shape in the height direction.

3. Offset Amounts of the Fins 44

As shown in FIG. 3, the intervals Po between the first rows 72 and second rows 74 include an interval Pot between a first row 72 and a second row 74 positioned on one side (upper side in the plane of the drawing) in the width direction of this first row 72 and an interval Po2 between the first row 72 and a second row 74 positioned the other side (lower side in the plane of the drawing) of this first row 72 in the width direction. Here, the interval Po2 is considered to be the offset amount of the second row 74 relative to the first row 72, and the offset amount is shown as a percentage of the interval P of the first row 72.

FIG. 4 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row 74 relative to the first row 72 is 0%. An offset of 0% means that there is no interval Po2 between the first row 72 and the second row 74, and that a fin 44′ that is continuous, instead of being intermittent, is provided. In the case where the offset amount is 0%, development of a temperature boundary layer in the coolant flowing on both sides of the fin 44′ is observed as the location progresses toward the downstream side.

FIG. 5 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row 74 relative to the first row 72 is 15%. In the case where the offset amount is 15%, development of a temperature boundary layer in the coolant flowing on the side (interval Pot side) where the flow path on the downstream side between the fin 44 of the first row 72 and the fin 44 of the second row 74 is narrow is observed, but the development of a temperature boundary layer in the coolant flowing on the side (interval Po1 side) where the flow path is wide is not observed, even on the downstream side.

FIG. 6 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row 74 relative to the first row 72 is 25%. In the case where the offset amount is 25%, the development of the temperature boundary layer is less than in the case where the offset amount is 15%.

FIG. 7 is a diagram simply showing the trend of the thermal contours in a case where the offset amount of the second row 74 relative to the first row 72 is 50%. In the case where the offset amount is 50%, development of the temperature boundary layer is not observed, even on the downstream side.

According to FIGS. 4 to 7, it is understood that if the offset amount is set to be even a small amount, the effect of restricting development of the temperature boundary layer is realized, and particularly if the offset amount is set to be greater than or equal to 25% and less than or equal to 50%, the effect of more effectively restricting the temperature boundary layer is realized. Based on the above, it can be said that it is preferable for the intervals Po between the first rows 72 and the second rows 74 to be greater than or equal to 0.25 P and less than or equal to 0.50 P (or greater than or equal to 0.50 P and less and or equal to 0.75 P).

4. Extension Amounts of the Fins 44

As described below, the extension amount is shown as a percentage of the half wavelength (=λ/2) of a waveform 60.

Extension Percentage=[{L−(λ/2)}/λ/2]×100(0%<Extension Percentage<50%)

FIG. 8 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 0%. In the case where the extension percentage is 0%, a large separation 80 occurs on the other side (lower side in the plane of the drawing) in the width direction of the upstream portion 56 of each fin 44.

FIG. 9 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 5%. In the case where the extension percentage is 5%, the separation 80 is less than in the case where the extension percentage is 0%.

FIG. 10 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 10%. In the case where the extension percentage is 10%, the separation 80 that occurs in the cases where the extension rate is 0% and 5% is almost nonexistent.

FIG. 11 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 30%, and FIG. 12 is a diagram simply showing the trend of a velocity vector distribution of the coolant in a case where the extension percentage is 40%. In the case where the extension percentage is greater than or equal to 30%, the separation 80 does not occur.

According to FIGS. 8 to 12, it is understood that if the upstream end 52 of a fin 44 extends even a small amount from the upstream side peak portion 48 along the waveform 60 or the downstream end 54 of the fin 44 extends even a small amount from the downstream side peak portion 50 along the waveform 60, an effect of restricting the occurrence of the separation 80 is achieved. In particular, if the extension percentage is greater than or equal to 30% and less than 50%, an effect of stopping the occurrence of the separation 80 is realized.

5. Amplitudes of the Fins 44

The length of a fin 44 in the width direction, i.e., the length of the fin 44 from the upstream side peak portion 48 to the downstream side peak portion 50 in the width direction, is referred to as the amplitude of the fin 44. FIGS. 13 to 15 are tables showing results obtained by examining the velocity vectors and temperature contours while using the fins with the respective amplitudes of 1 [mm], 3 [mm], and 5 [mm], and changing the offset amounts (25%, 37.5%, and 50%) and the extension amounts (0%, 15%, and 30%). According to FIGS. 13 to 15, it is understood that the velocity vectors and temperature contours do not significantly change as a result of different amplitudes. In other words, it is understood that there is no correlation between the amplitude, and the velocity vector and temperature contour.

6. Other Embodiments

In the embodiment described above, the fins 44 are described as having waveforms 60 that are sinusoidal curves. Instead of this, the same effect as in the embodiment described above can be realized with fins 44 having other waveforms 60. For example, as shown in FIG. 16, the fins 44 may have triangular waveforms 60.

7. Summary of the Present Embodiment

The fins 44 each have a flat shape in the height direction orthogonal to the flow direction f of the coolant in the coolant passage 12, and are provided intermittently along the virtual waveforms 60 that extend in the flow direction f and that make a plurality of rows in the width direction orthogonal to the flow direction f and to the height direction. With the fin 44 provided in the first row 72 being the first fin 44 and the two fins 44 lined up in the flow direction f and provided in the second row 74 adjacent to the first row 72 being the second fin 44 and the third fin 44, the upstream portion 56 including the upstream end 52 of the first fin 44 overlaps with the position in the flow direction f of the downstream portion 58 including the downstream end 54 of the second fin 44. Furthermore, the downstream portion 58 including the downstream end 54 of the first fin 44 overlaps with a position in the flow direction f of the upstream portion 56 including the upstream end 52 of the third fin 44.

With the configuration described above, it is possible to restrict the development of the temperature boundary layer by providing the fins 44 intermittently in the flow direction f of the coolant. Furthermore, by causing the positions of the upstream portion 56 of the first fin 44 provided in the first row 72 and the downstream portion 58 of the second fin 44 provided in the second row 74 adjacent thereto to overlap in the flow direction f and also causing the positions of the downstream portion 58 of the first fin 44 provided in the first row 72 and the upstream portion 56 of the third fin 44 provided in the second row 74 to overlap in the flow direction f, it is possible to restrict the flow of the coolant from separating from the fins 44. With the structure described above, favorable heat transfer can be realized between the fins 44 and the coolant.

The fins 44 are provided along portions of the waveforms 60 including two peaks 62. With the configuration described above, development of the temperature boundary layer and separation of the flow of coolant are further restricted, and favorable heat transfer can be realized between the fins 44 and the coolant.

The waveforms 60 each have shapes symmetrical on the axis that is the virtual line 70 that passes through the peaks 62, is orthogonal to the flow direction f, and is parallel to the width direction. With the configuration described above, the separation of the flow of coolant is further restricted, and favorable heat transfer can be realized between the fins 44 and the coolant.

The fins 44 each have the same shape in the cross-sectional planes parallel to the flow direction f and to the width direction. With the configuration described above, favorable heat transfer can be realized over a wide range, with coolant flow that is substantially uniform in the height direction.

In a case where the length of a half wavelength of the waveform 60 in the flow direction f is λ/2 and the length of the fin 44 in the flow direction f is L, [{L−(λ/2)}/λ/2]×100 may be greater than or equal to 30% and less than 50%. With the configuration described above, the effect of preventing the occurrence of the separation 80 is realized.

The cooling apparatus according to the present embodiment is not limited to the embodiments described above, and it is obvious that various configurations can be adopted without deviating from the scope of the present invention. 

What is claimed is:
 1. A cooling apparatus comprising a plurality of fins within a coolant passage near a heat source body, wherein the plurality of fins each have a flat shape in a height direction orthogonal to a flow direction of coolant in the coolant passage, and are provided intermittently along virtual waveforms that extend in the flow direction and that make a plurality of rows in a width direction orthogonal to the flow direction and to the height direction, and with a fin provided in a first row being a first fin and two fins lined up in the flow direction and provided in a second row adjacent to the first row being a second fin and a third fin, an upstream portion including an upstream end of the first fin overlaps with a position in the flow direction of a downstream portion including a downstream end of the second fin, and a downstream portion including a downstream end of the first fin overlaps with a position in the flow direction of an upstream portion including an upstream end of the third fin.
 2. The cooling apparatus according to claim 1, wherein the fins are provided along portions of the waveforms including two peaks.
 3. The cooling apparatus according to claim 2, wherein the waveforms have shapes symmetrical on an axis that is a virtual line that passes through the peaks, is orthogonal to the flow direction, and is parallel to the width direction.
 4. The cooling apparatus according to claim 1, wherein the fins each have the same shape in cross-sectional planes parallel to the flow direction and to the width direction.
 5. The cooling apparatus according to claim 1, wherein in a case where a length of a half wavelength of the waveform in the flow direction is λ/2 and a length of the fin in the flow direction is L, [{L−(λ/2)}/λ/2]×100 is greater than or equal to 30% and less than 50%. 